Ciguatera poisoning

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Ciguatera poisoning is an uncommon toxicity associated with consumption of various large, predatory, tropical reef fish that have bioaccumulated ciguatoxins[1].

Ciguatoxins are produced by photosynthetic dinoflagellate Gambierdiscus toxicus. The dinoflagellate normally causes the 'red tide' phenomenon known as an algal bloom[2].

This neurotoxin is stored in the liver and viscera of fish that have eaten the dinoflagellate and concentrates up the food chain towards progressively larger species, including dog and humans[3]. The prevalence of ciguatera in the South Pacific increases dramatically where average sea surface temperatures are at least 28 to 29°C[4].

Since the toxin is heat stable, cooking does not destroy the toxin, no matter how well the fish is cooked. Contaminated fish, when consumed, will cause poisoning.

Poisoning in dogs is characterized by characterized by various gastrointestinal, cardiovascular, and neurologic symptoms such as vomiting, diarrhea, ataxia, head shaking, nystagmus and paralysis[5].

Death usually occurs as a result of respiratory and heart failure.

A prolonged period of acute illness can result, and the neurologic symptoms can last months, with variable asymptomatic and symptomatic periods.

Diagnosis is based on history of fish consumption and exclusion of other causes.

A differential diagnosis would include botulism, organophosphate toxicity, tetanus and tetrodotoxin poisoning.

Treatment is usually supportive with intravenous fluids and antioxidants such as acetylcysteine as well as thiamine.

Dog may eventually recover but may require up to a week of hospitalization.

References

  1. Rongo T & van Woesik R (2013) The effects of natural disturbances, reef state, and herbivorous fish densities on ciguatera poisoning in Rarotonga, southern Cook Islands. Toxicon 64:87-95
  2. Hajar Albinali HA (2011) Ciguatera fish poisoning. Heart Views 12(4):165
  3. Centers for Disease Control and Prevention (CDC). (2013) Ciguatera fish poisoning - New York City, 2010-2011. MMWR Morb Mortal Wkly Rep 62(4):61-65
  4. Llewellyn L (2010) Revisiting the association between sea surface temperature and the epidemiology of fish poisoning in the south Pacific: reassessing the link between ciguatera and climate change. Toxicon 56:691–697
  5. Oh SY et al (2012) Reversible cerebellar dysfunction associated with ciguatera fish poisoning. J Emerg Med 43(4):674-676